rbavery commented on code in PR #1221:
URL: https://github.com/apache/sedona/pull/1221#discussion_r1482151468
##########
common/src/main/java/org/apache/sedona/common/raster/MapAlgebra.java:
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@@ -437,6 +437,90 @@ public static double[] normalize(double[] band) {
return result;
}
+ public static GridCoverage2D normalizeAll(GridCoverage2D rasterGeom) {
+ return normalizeAll(rasterGeom, 0d, 255d, -9999, -99999, -99999);
+ }
+
+ public static GridCoverage2D normalizeAll(GridCoverage2D rasterGeom,
double minLim, double maxLim) {
+ return normalizeAll(rasterGeom, minLim, maxLim, -9999, -99999, -99999);
+ }
+
+ public static GridCoverage2D normalizeAll(GridCoverage2D rasterGeom,
double minLim, double maxLim, double noDataValue) {
+ return normalizeAll(rasterGeom, minLim, maxLim, noDataValue, -99999,
-99999);
+ }
+
+ /**
+ *
+ * @param rasterGeom Raster to be normalized
+ * @param minLim Lower limit of normalization range
+ * @param maxLim Upper limit of normalization range
+ * @param noDataValue NoDataValue used in raster
+ * @param minValue Minimum value in raster
+ * @param maxValue Maximum value in raster
+ * @return a raster with all values in all bands normalized between minLim
and maxLim
+ */
+ public static GridCoverage2D normalizeAll(GridCoverage2D rasterGeom,
double minLim, double maxLim, double noDataValue, double minValue, double
maxValue) {
+ if (minLim > maxLim) {
+ throw new IllegalArgumentException("minLim cannot be greater than
maxLim");
+ }
+
+ // Unset minmaxFlag if minValue and maxValue are not given;
+ boolean minmaxFlag = minValue != -99999;
+
+ int numBands = rasterGeom.getNumSampleDimensions();
+ RenderedImage renderedImage = rasterGeom.getRenderedImage();
+ int rasterDataType = renderedImage.getSampleModel().getDataType();
+
+ for (int bandIndex = 1; bandIndex <= numBands; bandIndex++) {
+ // Get the band values as an array
+ double[] bandValues = bandAsArray(rasterGeom, bandIndex);
+
+ // Find min and max values in the band, excluding NoDataValue
+ if (!minmaxFlag) {
+ minValue = Arrays.stream(bandValues).filter(val -> val !=
noDataValue).min().orElse(Double.NaN);
+ maxValue = Arrays.stream(bandValues).filter(val -> val !=
noDataValue).max().orElse(Double.NaN);
+ }
+
+ if (minValue == maxValue) {
+ // Set default value for constant bands to minLim
+ Arrays.fill(bandValues, minLim);
+ } else {
+ // Normalize the band values, setting NoDataValue to maxLim
+ for (int i = 0; i < bandValues.length; i++) {
+ if (bandValues[i] == noDataValue) {
+ bandValues[i] = maxLim;
Review Comment:
@jiayuasu setting noDataValue to the maxLim by default will corrupt real
data values.
instead I think the default should be to scale real values from 0, 254 and
set the noDataValue to 255 if it is not given.
Or, scale real values between 1-255, set noDataValue to 0 by default. this
makes more sense to me, 0 is used as a noDataValue more often than 255.
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